In the field of document feeding, separating, and sorting there have been many different mechanisms and devices designed to feed and to convey or transport such documents along a path wherein it is important that each and every document being transported follows in successive manner and that two or more documents do not overlap during the time of transport.
Several of such designs include the use of a drive member cooperating with an adjacent member which may be driven in the opposite or counter rotation, the use of an idler member driven at a slower speed than the drive member, and the use of retardant materials in the idler structure to restrict the passage of a plurality of documents past a given station. Various ways and means of accomplishing certain results include the use of frictional surfaced belts or rollers which are somewhat controlled with pressure or resilient means, linkages, or variations in symmetry to provide a variable throat for passage of only one document at any one time.
Representative prior art in the document separating field includes U.S. Pat. No. 3,025,051 issued to B. F. David et al. which discloses sheet handling apparatus and method wherein a separator or drive wheel cooperates with a restraint belt driven in the opposite direction, the belt being tensioned by means of an idler pulley carried on a lever which is biased by a spring to provide an adjustable throat between the wheel and the belt. U.S. Pat. No. 3,635,465 issued to J. Beery discloses a document separator control system wherein a drive wheel cooperates with a belt trained around a pair of guide wheels, there being a pair of movable guide rollers carried on a Y-member and connected to the guide wheels by links, with the Y-member being directly actuated by a linear actuator to provide altering of the path of the belt to maintain the frictional forces. And, U.S. Pat. No. 3,861,670 issued to W. A. Kraft discloses sheet feeding apparatus wherein a feed roller is carried on a shaft and cooperates with a retard roller, the feed roller having a first portion engaging with the retard roller and a second portion engaging the sheet. The retard roller is eccentrically carried on a shaft which is pivotally biased by a spring to move the retard roller between operative and inoperative positions.